Frequency State / Music Production Reference Library · Volume 5
A delay records or holds a signal briefly and reproduces it later. One repeat produces a simple echo; feeding the delayed signal back into itself creates a sequence of repeats. Delays are useful for rhythmic space, musical call-and-response, dub textures and experimental sound design.
Delay time and the rhythm of repeats
Delay time is the gap between the original sound and its repeat. Some processors specify it in milliseconds, while others synchronise it to note lengths such as a quarter note, eighth note or dotted eighth note.
At 120 BPM, a quarter-note lasts 500 milliseconds and an eighth-note 250 milliseconds. The relationship is 60,000 divided by BPM for a quarter-note duration in milliseconds. When tempo synchronisation is disabled, delay time can create more irregular movement or short doubling effects.
Feedback: how echoes continue
Feedback routes some of the delayed output back to the delay input. A low setting produces only a few audible repetitions; a high setting extends the series and can create sustained textures. Some units include filtering or saturation in the feedback path so each repeat becomes darker or more distorted.
Very high feedback can lead to runaway level or self-oscillation. Start quietly, especially with headphones, and use a level limiter or mute control if available. Intentional feedback is a useful sound-design technique, but it must be monitored.
Dry/wet mix and insert versus send
On an insert, the wet/dry control balances the original and delayed signals. For a shared send return, setting the effect to fully wet usually avoids creating a second copy of the dry source.
A delay return can be filtered, compressed or distorted independently. This is a straightforward way to produce echoes that sit behind a lead vocal or percussion part without masking the original attack.
Slapback, doubling and longer echoes
A short single repeat can make a vocal or guitar feel larger, especially when the delayed sound is lower in level than the original. Slapback echoes are often perceptible as a distinct reflection rather than a rhythmic series.
Very short delays can introduce comb-filtering when blended with a correlated dry signal; slightly longer differences may suggest doubling. Delays extending across beats create repeated musical events and can become part of the composition rather than a background effect.
Stereo and ping-pong delay
A stereo delay can use different repeat times or levels in the left and right channels. Ping-pong delay alternates repeats between sides, creating an obvious sense of movement across the stereo field.
Compare the result in mono to check for unwanted cancellation or excessive changes in level. Stereo movement should support the musical arrangement rather than distract from the main rhythm.
Filters, pitch and modulation in the feedback path
Filtering successive repeats can imitate some of the characteristics of tape or analogue echo systems, where high frequencies may gradually fade. Saturation and modulation can further change the tone, producing flutter, instability or harmonic colour.
Frequency-shifting and pitch-shifting feedback create different kinds of movement. A pitch-shifted repeat can climb or descend by musical intervals; a frequency shifter adds a fixed amount in hertz, often producing more dissonant evolving patterns.
Working with reverb and delay together
Delay produces repeats that remain individually recognisable under many settings, while reverb generally produces a dense field of reflections. In practice the distinction is not absolute: short repeated reflections can blend into a reverberant effect, and a reverb algorithm may contain many internal delays.
A delay feeding a reverb can make each repeat bloom in space; a reverb feeding a delay may echo an already diffuse sound. Both can work, but they fill different amounts of rhythmic and spectral space.
A practical delay experiment
Make a four-bar drum or synth phrase at 120 BPM. Place a delay on a send return, begin with a 250 ms repeat and low feedback, then switch to 500 ms. Notice how the repeats move from an eighth-note relationship to quarter-note timing.
Increase feedback gradually, then filter the return to make each repetition less bright. Finally compare the delay in mono and stereo, and lower the return until the rhythmic pattern remains clear.
Continue reading
Compare the effect with Reverb Explained and read Stereo vs Mono for spatial placement. Gain Staging Explained is particularly relevant when experimenting with strong feedback.